Auxiliary Input Unit - problem

I have an auxiliary input unit which is connected to some external PIRs. The idea is that when the PIR triggers (only does so at night), a C-Bus channel switches on and then off again after a timer.

The slight fly in the ointment is that the PIR remains triggered for 60 seconds after the movement ceases. So, I have a very short delay on the timer so the C-Bus group stays on for just a few seconds after the PIR releases.

To achieve that, I have the unit programmed as:

Short Press - Onkey;
Short Release - Retrig;
Long Press - Idle;
Long Release - Retrig;

After 5 seconds, the timer sends an Offkey.

Most of the time this works correctly. The light comes on as soon as the PIR triggers and goes off again just over a minute later. Very occasionally though, the light stays on for ever. The problem is easily cured by walking in front of the PIR when, lo and behold, the light goes off after just over a minute. It is a little inconvenient to have to wander outside at 3:00am to repair the illumination caused by a passing cat!

I have not managed to come up with any logical explanation for the unusual behaviour.

Ideas appreciated,

Nick

 

I assume that there is only one PIR per C-Bus Group Address.

If so, try ONKEY/OFFKEY/IDLE/OFFKEY. The timer values and the Expiry command are then irrelevant. This will confirm if the C-Bus network is the issue or the PIR is. Note that you will not have any "run on" (currently 5 sec).

If it behaves as it currently does, i.e. you still have to walk past in the dead of night, then the PIR is locking up and C-Bus is just following.

Just my thoughts.

 

Another option is to configure the aux input to simulate a bell press button (ONKEY/OFFKEY/ONKEY/OFFKEY). The PIR then does the timing for you, and all C-Bus needs to worry about is whether the PIR's contact is open or closed.

 

Hi Nick
I do something similiar with my setup and the following works for me.


recall1
idle
retrig
idle

HTH
Frank

 

Thanks Guys

Thanks all for the prompt responses. I have realised that I was trying to overcomplicate things - I hadn't realised until quite late on that the PIR stayed triggered for one minute, so had previously gone down the timer route.

In reality, the ONKEY / OFFKEY / ONKEY / OFFKEY is the obvious way to go and seems to work fine. So, thanks for bringing my thinking back to the right planet!

 

GJD Elite PIR - all horribly wrong again!

It worked while I only had one PIR! Now, all four (all GJD Elite) are connected:

- 12v to each PIR;
- 0v to each PIR;
- 12v to all four "B" terminals in CBus aux input unit;
- S from PIR 1 to A1, S from PIR 2 to A2, and so on.

All four CBus channels are set to ONKEY/OFFKEY/ONKEY/OFFKEY as that seems to be the simplest setting.

When any PIR triggers, the appropriate group switches on. This is as expected, but works provided only one PIR is triggered.

As soon as more than one is triggered at the same time, both groups switch on as expected. As soon as the first Elite times out, its group switches off as I would expect. However, the second group (and the orange light on the aux unit) starts to oscillate on and off around once per second. While that is happening, the first PIR will not trigger again. As soon as the second PIR times out, everything is back to normal.

It seems as if the aux input is not happy with the PIRs connected the way I have them. The S output on the Elite is an open collector output. The aux input module says it will work with open collector outputs. I'm obviously missing something though.

Does anyone know the correct way to interface the S output of a GJD Elite to a CBus aux input unit?

Thanks,

Nick

 

The inputs on both the DIN and the regular AUX units are labelled 1A & 1B for channel 1, 2A & 2B for channel 2, 3A & 3B for channel 3 and 4A & 4B for channel 4.

Can you please clarify that you mean the 1A and 2A inputs and that the 1B, 2B etc inputs are unconnected? You will need to connect the B inputs of the AUX unit to the same 0V that is connected to the PIR's for this to work properly. This is detailed on page 3 of the 5504AUX instructions: http://www.clipsal.com/cis/pdf_files/1036391_-_5504AUX_INSTALLATION_INSTRUCTION.pdf

 

Not quite!

I have the PIR "S" connections to 1A, 2A, 3A and 4A respectively. 1B, 2B, 3B and 4B are all connected to +12V.

Firstly this felt right because the Elites have open collector outputs which, I assumed, meant floating when inactive and pulled down to ground when active. That seemed to say that I needed a 12v supply in there somewhere.

Secondly, I did try commoning the 0V on the 1B, 2B, 3B, 4B and then nothing seemed to happen ever.

Do I perhaps have an impossible problem and will need to have the PIR open collector outputs driving a small relay and use the relay contacts to connect A1 to B1, etc?

Cheers

Nick

 

I'm a bit suprised that it works (sort of) with the B terminals connected to 12V and doesn't work when connected to 0V. It suggests some marginal state of operation.

The unit works by supplying a small amount of isolated AC power (about 5 volts) to the terminals and measuring the current that flows between them. If the open-collector output has too high a series resistance then the unit won't register the contact as closed because insufficient current will flow.

I imagine that, being an open collector output, the PIR manufacturer has a series resistance in their device to reduce the likelihood of damage to the semiconductor doing the switching. This is reducing the current from the AUX unit and is therefore not registering the signal correctly that the contact is "closed". If that's what's happening then you'll need to use a small relay to interface between the two.

 

Relay did it

Thanks for that. I now have four neat little DIN rail mounted relays. The PIRs work them just fine. The relay contacts present a nice voltage free interface to the Aux unit, so that's happy too.

Ta for all your help.

Nick